Mapping of Genomic Regions for Biochemical and Physiological Parameters Contributing Towards Drought Tolerance in Horsegram (Macrotyloma uniflorum (Lam.) Verdc.).

Abstract

Horsegram (Macrotyloma uniflorum (Lam.) Verdc.) is a drought hardy legume which can be grown in varied soil and temperature regimes. Though it has numerous, nutritive and medicinal benefits, it still lags behind other legumes in terms of genomic resources and genetic improvement. This crop is mostly cultivated on marginal and drought-prone area; thus, genetics of drought stress tolerance can be understood by studying the various drought parameters. To get insight, quantitative trait loci for drought-tolerant traits were identified using an intraspecific mapping population of 162 F8 recombinant inbred lines derived from a cross between HPKM249 and HPK4. The linkage map already developed was used along with the phenotypic data for biochemical and physiological parameters to identify genomic regions which are linked to drought tolerance. In the study, a total of seven QTLs were identified for ten different drought-related traits. One QTL for malondialdehyde content on linkage group 2, two QTLs for root length on linkage groups 3 and 9, one QTL each for proline and chlorophyll content under drought stress on linkage group 4, and one QTL each for root dry weight and root fresh weight on linkage group 5 were identified using composite interval mapping. The identified QTLs will be utilized in marker-assisted breeding and increase our understanding on the physiology of drought stress tolerance.